stainless steel bolt

I have a 94' Hunter 19 galvanized trailer full of rusted bolts and I want to replace them all. What type or grade should I replace them with? (I want to replace them with stainless steel, but I am unsure they have the sheer strength, specially the bolts that hold metal that the bunk rest on) I...

The sheaves on my boom are obviously way passed expired, so... I tried to remove the boom ends so I could access the sheaves, and they (the aluminum boom caps) were held in with stainless steel bolts. The last time I ran into this the 3/8” bolt had a hex head. This time it is maybe an 8-32...